Get XL. I'm 5'8" and I have obermeyer reverts in size large, and they're pretty baggy, but I could definatly step it up if I wanted.
You can kind of see it in this picture. But keep in mind they are tighter cause my knee is bent, and I have them tight up on my waist when I'm shooting, I only sag when I'm riding. So large would fit fine, but if you are the extra steezy type, get XL